B Resonance relationship with glass shatter

[TT0]

Just to check my understanding:

-The glass will only break when the sound is at the resonant frequency of the glass.
-This creates standing waves in the glass.
-The glass will only shatter if the sound is at a high enough volume (amplitude)
-Otherwise, at a lower volume at resonant frequency, no matter the duration, the glass will vibrate but not shatter
(resonance will cause the secondary object to vibrate at a certain energy but the object won't have increasing energy over time right?)

Could you please confirm my understanding?

Thanks a lot!

 

[DrClaude]

Correct. The reason why volume matters is that there is some dissipation.

A nice video on the subject:

 

[TT0]

I see, that is a very nice video, thanks! So the vibrating glass is a form of standing waves right?

Also, since it took some time for the glass to break is it because despite the vibrations being of the same energy, each vibration weakens the structure of the glass and after enough weakening the glass shatters and not that a greater vibration occurs successively in the glass? (I am thinking about the swing analogy where each push will cause the swing to rise higher than previously, but I don't think it is the case for resonance, would you please confirm this.)

Thanks again

 

[CWatters]

I would argue with "_only_ breaks at resonance". It might also break if subject to a very loud sound not at resonance.

The important thing to understand is that the maximum amount of power is transferred from the source to the load at resonance. The power transferred at other frequencies could still be enough to break it.

 

[tech99]

Just to check my understanding:

-The glass will only break when the sound is at the resonant frequency of the glass.
-This creates standing waves in the glass.
-The glass will only shatter if the sound is at a high enough volume (amplitude)
-Otherwise, at a lower volume at resonant frequency, no matter the duration, the glass will vibrate but not shatter
(resonance will cause the secondary object to vibrate at a certain energy but the object won't have increasing energy over time right?)

Could you please confirm my understanding?

Thanks a lot!

Your statements seem to be correct. The glass could also shatter away from resonance if the amplitude was much greater.
This is my description in more detail:-
When the sound commences, the first wave will exert sound pressure against the glass, which will deflect slightly. Some of the energy will be dissipated as heat in bending the glass, but the majority will be stored in resonance as kinetic energy and elastic potential energy. The resonance mainly involves the bending of the glass rather than the volume of air in the glass. Each wave will cause the resonance to build up in amplitude as more energy is stored and also dissipated. The growth process is relatively slow, depending on the ratio of energy stored/energy dissipated per cycle. This is also called the Q of the resonator and may be in the order of 1000. The glass will also re-radiate sound, and when the energy dissipated equals half the incident energy, no more growth will occur.
The amplitude of the glass resonance is in quadrature to the incoming sound wave, and is proportional to Q. So it can be very large, larger than the sound wave displacement, as it is in quadrature to it. If this amplitude stresses the glass beyond its ultimate strength then the glass will break. If the sound ceases, the stored energy will gradually dissipate as heat and sound radiation.